So I was able to unsolder all three motor wires after a lot of choice words and hours of attempting to melt the factory solder. Once removed, the wires are soldered to small, slightly raised circular pads on the lower circuit board. They solder on quite easily, and the results have me happy it is not a one-and-done ESC.

Long story short - it can be done. Just have some strong drinks ready when the going gets tough.